Which enzyme is responsible for linking the fragments of $DNA$?

For how long should bacteria be cultured in a $^{14}N$ medium after being transferred from a $^{15}N$ medium so that the extracted $DNA$ consists of equal amounts of hybrid $DNA$ and light $DNA$?

Ten $E. coli$ cells with $^{15}N$-dsDNA are incubated in a medium containing $^{14}N$ nucleotides. After $60$ minutes, how many $E. coli$ cells will have $DNA$ totally free from $^{15}N$ (in $cells$)?

Experiments involving the use of radioactive thymidine to detect the distribution of newly synthesized $DNA$ in the chromosome were performed on which plant?

Which of the following processes is related to reverse transcription?

$DNA$ replication is semi-conservative as